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Re: [TCML] air core
With care you can create a coil with no former at all..
If you make a thick paper former and coat the out side with wax
paper. Wind the coil onto the wax paper and coat with multiple layers of
varnish until you have a really thick coating. Carefully fold the inner
paper tube in on its self and remove from the coil. You now have a coil
held together with only varnish.
I have made a couple of these, and I have seen no changes in
properties from a coil wound in a more conventional way. The coils do
look good on their own, but when you have added a top load and a
primary, they look almost exactly the same as a regular coil.
I'm my opinion, not worth the extra hassle for a flimsy coil compared to
using a more solid former.
On 11/11/2012 18:42, Ed Phillips wrote:
As long as the form is clean and dry enough that there isn't any
discharge along the surface the performance will be pretty much
independent of the material. I've experimented quite a bit with
making coils for receivers using various forms of PVC tubing, ordinary
mailing tubes with or without drying and sealing, and even a piece of
wood and couldn't tell any difference in the Q at 4 MHz, well above
the frequency of most TC's. The purpose of these particular tests was
a report that some forms of black and grey PVC pipe were quite lossy
when used for coil forms and that sure wasn't true for my cases.
I certainly agree about the 'art and appearance' business. A neatly
wound coil on a 'good looking' form can be a real thing of beauty!
Jim Lux wrote:
On 11/10/12 3:32 PM, JJR+weluvlucy.com wrote:
Hello to the list,
Has anyone ever built a secondary coil without a coil-form. Wouldn't
be the ideal coil-form because it has a dielectric constant of 1?
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